Inactivation of bacteria inoculated inside urinary stone-phantoms using intracorporeal lithotripters

Intracorporeal lithotripsy is used to treat a high percentage of urinary calculi. Urinary calculi may contain bacteria, which might cause septicemia after lithotripsy; however, little is known about the effects of lithotripters on the viability of microorganisms inside renal calculi. The objectives of this study were to evaluate the bactericidal effect, and the potential effect on intra-bacterial protein release of four different intracorporeal lithotripters on Escherichia coli (E. coli) inoculated inside artificial kidney stones. An electrohydraulic, a pneumatic, an ultrasonic, and a holmium-laser lithotripter were used to pulverize a set of infected kidney stones inside a test tube containing a saline solution. Two different energy levels were tested per lithotripter. The stones were manufactured by mixing gypsum cement and Vel-mix-stone with a suspension containing E. coli. Results were analyzed by analysis of variance. The release of intracellular protein was measured with a spectrophotometer. Bacteria inactivation was observed with all lithotripters. The highest percentage of inactivated bacteria was obtained with the electrohydraulic lithotripter. The smallest effect was observed using the holmium-laser lithotripter. A relatively high amount of intracellular protein was released into the saline solution after stone pulverization. Intracorporeal lithotripters inactivate a high percentage of bacteria during stone comminution; however, intracellular protein is released, increasing the probability of septicemia.